Using the Command Line

The command line is an essential tool for systematic PC troubleshooting. It is a text-based interface that allows direct communication with Windows OS to diagnose and repair PC issues. Unlike the Task Manager that provides graphical elements to visualize problems, the CLI uses commands that follow a structured syntax consisting of the command name followed by optional parameters and arguments the system interprets as instructions that modify its behavior.

At the most fundamental level, a Layer 1 technician's use of the command line is rooted in the need to validate whether a physical pathway can actually carry usable traffic. The concepts at play begin with link state, the confirmation that a network interface card (NIC) is detecting signal on the wire, since a lit port LED alone is not sufficient proof. From there, the technician must verify addressing, whether through DHCP lease assignment or manual static configuration, because the presence or absence of an IP reveals if Layer 2 frames are making it to a DHCP server or peer device. Once an address is in place, packet flow can be tested with simple tools like ping, which confirms not only transmission and reception but also the integrity of the path across the immediate cable and switch segment.

Equally important are local validation mechanisms such as loopback testing, which isolates the NIC and TCP/IP stack from external dependencies, and resolution and table states, including ARP and routing entries, which can either confirm or obscure whether a physical link is working as intended. The overarching concept is fault domain isolation: separating the potential points of failure into clear categories -NIC config vs. port, port vs. cable, local stack vs. remote device. The command line is not being used here to solve higher-level routing or application problems but to establish, in an unambiguous and methodical way, whether the wire, the port, and the interface are capable of basic communication. The commands help prove whether the port, cable, and interface are physically passing signal.

When your computer has problems, built-in command tools can quickly fix common issues. Slow PC performance can be resolved by checking memory usage and scanning for disk errors. Printer connection problems often fix themselves by restarting the print service and testing network communication. No sound? Windows includes automated troubleshooters that detect and repair audio issues. Keyboard, mouse, or display problems typically resolve by restarting specific services and updating drivers. These simple diagnostic steps solve most everyday computer issues without expensive service calls.

1. Utility Commands

   List Directories

   dir

   Display DIR Pathways

   tree

   Change Directories

   cd..

   Display Help Info

   help

   Close Command Prompt

   exit

   Display HTML File Contents

   type (filename.html)

   Check Print Spooler

   net stop spooler -> net start spooler

2. Slow Running PC

   Check Running Processes

   tasklist

   End Processes

   taskkill /programname.exe /f

   Check Disk Usage

   dir C:\

   Scan for Disk Errors

   chkdsk C: /f

   Check System Files

   sfc /scannow

3. Printer Connectivity Issues

   View Printer Details

   devmgmt.msc (Right-click Printers > Properties > Details > Physical Device Object Name)

   Check Firewall Settings

   firewall.cpl (Allow File/Printer Sharing)

   Test Printer Connection

   ping [printer-ip-address]

   telnet [new-printer-IP] 9100

   Check Printer IP Config

   arp -a (Look for MAC Address)

   Add Printer IP Address

   control printers (Add Printer -> TCP/IP address)

   Check Print Spooler

   net stop spooler -> net start spooler

   Clear Print Queue

   net stop spooler del %systemroot%\System32\spool\printers\*.*

4. Audio Issues (No Sound)

   Run Audio T/S

   msdt.exe -id AudioPlaybackDiagnostic

   Restart Audio Services

   net stop audiosrv -> net start audiosrv

   Update Audio Drivers

   devmgmt.msc

5. Keyboard & Mouse Issues

   Restart HID Services

   net stop hidserv -> net start hidserv

   Update Device Drivers

   devmgmt.msc

6. Display/Resolution Issues

   Check Display Settings

   desk.cpl (Select 'Detect')

   Update Graphics Driver

   devmgmt.msc (Select 'Display Adapters')

   Run DX Diagnostic Tool

   dxdiag (Select 'Display')

Critical system failures require advanced diagnostic tools beyond basic troubleshooting. Commands like bootrec /rebuildbcd, bcdedit /enum, and safe mode through msconfig can repair damaged boot configurations and startup problems. Windows Update failures often need cache clearing via service stops and automated troubleshooters. System restore using rstrui.exe provides rollback options for severe corruption, while hardware diagnostics through chkdsk /f /r and SMART status checks identify failing components before complete system failure. Event Viewer and advanced system tools like eventvwr.msc and systeminfo reveal configuration conflicts and hardware issues that prevent normal operation.Retry

1. System Tools

   Display Logged-In User

   whoami or hostname

   User Credentials

   cmdkey /list

   Windows Version Info

   winver

   Windows Update Check

   wuauclt /detectnow

   Verify Software Auth

   sigverif.exe

   Display PC Config

   systeminfo

   Launch System Info

   msinfo32

   Launch System Config

   msconfig

   Launch System Restore

   rstrui.exe

   Launch Device Manager

   devmgmt.msc

   Launch Disk Manager

   diskmgmt.msc

   Launch Services Console

   services.msc

   Launch Event Viewer

   eventvwr.msc

   Launch Performance Monitor

   perfmon.msc

   Launch Resource Monitor

   resmon.exe

   Display Run Processes

   tasklist

   End Processes

   taskkill /programname.exe /f

2. Booting Issues

   Try Safe Mode Boot

   msconfig (Select 'Safe Boot' under Boot options)

   Check Hard Drive

   chkdsk C: /f /r

   System Restore

   rstrui.exe

   Use Startup Repair

   bootrec /scanos

   bootrec /rebuildbcd

   Check Boot Config

   bcdedit /enum

   Repair Boot Files

   sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows

   Check Print Spooler

   net stop spooler -> net start spooler

   Clear Print Queue

   net stop spooler del %systemroot%\System32\spool\printers\*.*

3. Windows Update Failures

   Clear Update Cache

   net stop wuauserv

   rd /s /q C:\Windows\SoftwareDistribution

   net start wuauserv

   Run Windows Update T/S

   msdt.exe -id WindowsUpdateDiagnostic

4. System Restore & Recovery

   System Restore Status

   vssadmin list shadows

   Enable System Protection

   sysdm.cpl (Configure to Turn On)

   Run System Restore

   rstrui.exe

5. Hardware Concerns

   Check Disk Health

   chkdsk C: /f /r

   Run System File Check

   sfc /scannow

   Check Disk Space

   dir C:\ (Ensure 15% free space)

   Run System File Check

   sfc /scannow

   Check SMART Status

   wmic diskdrive get status

   Check Logs for Errors

   eventvwr.msc

6. Software and APP Issues

   Clear Browser Cache and Data (Chrome)

   rd /s /q "%LOCALAPPDATA%\Google\Chrome\User Data\Default\Cache"

   rd /s /q "%LOCALAPPDATA%\Google\Chrome\User Data\Default\Code Cache"

   Clear Browser Cache and Data (Explorer)

   rundll32.exe InetCpl.cpl,ClearMyTracksByProcess 255

   Reset Browser Settings (Chrome)

   chrome.exe --reset-variation-state

   Check Browser Extensions (Chrome)

   chrome.exe --disable-extensions

   Check Defaulat Browser Settings

   appwiz.cpl

   Reset Internet Options

   inetcpl.cpl

   Check for Malware

   msrt.exe -> sfc /scannow

   Delete Temporary Files

   cleanmgr.exe -> del /q/f/s %TEMP%\*

Network connectivity problems require systematic testing from basic hardware up through application layers. Start by verifying network adapter capabilities with wmic nic commands and checking connection speeds through ncpa.cpl, then test basic connectivity using ping and tracert to identify where communication breaks down. DNS issues often cause slow browsing despite good connectivity - use nslookup to test DNS performance and ipconfig /flushdns to clear corrupted entries, or switch to alternative DNS servers like 8.8.8.8 for testing. Wi-Fi problems require signal strength analysis through netsh wlan show interface and profile management, while complete network resets using netsh winsock reset and IP configuration renewal can resolve stubborn adapter issues. Layer-by-layer troubleshooting prevents wasted time on complex solutions when simple connectivity or DNS problems are the root cause.

1. NIC Capability

   Ascertain NIC

   wmic nic where (NetEnabled=true) get Name,Speed

   Configure NIC

   devmgmt.msc Expand Network Adapters > Right-click your network adapter > select Properties > Enter Advanced tab > Speed & Duplex > Auto Negotiation or Auto > OK, reboot

2. Testing Internet Connectivity (Slow Speed)

   Ethernet Speed

   ncpa.cpl Right-click Network Adapter > Status > Details

   Display Cached IPs

   arp -a

   Trace Network Route

   tracert (Address)

   Validate IP (Test Speed)

   ping google.com

   ping (assigned IP)

   Check DNS Performance

   nslookup (hostname)

   Flush and Reset DNS

   ipconfig /flushdns

   netsh int ip reset

   Check Network Usage

   resmon.exe

   Check Network Adapters

   devmgmt.msc

   Test Diff DNS Server

   netsh interface ip set dns "Wi-Fi" static 8.8.8.8

3. Testing Internet Connectivity (Poor Connection)

   Check Signal Strength

   netsh wlan show interface

   Display Wi-Fi Adapters

   netsh wlan show drivers

   Display Wi-Fi Standards

   netsh wlan show wirelesscapabilities

   Display Network Profiles

   netsh wlan show profiles

   Display Network Details

   netsh wlan show profile "NetworkName"

   Reset Network Adapter

   netsh winsock reset

   netsh int ip reset

   ipconfig /release

   ipconfig /renew

   ipconfig /flushdns (Restart PC)

   Reset Network Settings

   netsh winsock reset catalog

   netsh int ipv4 reset reset.log

   netsh int ipv6 reset reset.log

When troubleshooting, adhere to these best practices: